S. pneumoniae has a pilus known as pilus-1 encoded by a 14-kb islet (PI-1) having seven genes encoding: the RlrA transcriptional regulator, three pilus subunits with LPXTG-type cell wall sorting signals, and three sortase enzymes involved in synthesis of the pilus polymer and in the incorporation of ancillary pilus components. RrgB is the major subunit that forms the backbone of the structure, while the other two pilins (RrgA, RrgC) are ancillary structural proteins [1-4]. RrgA is the major pilus-1 adhesin; bacteria lacking RrgA are less adherent to epithelial cells than wild-type organisms.